Age-graded change in the initiation of positive affect
This study presents data on the initiation of positive affect during mother-child interaction in 12- (n = 31), 18- (n = 28), 24- (n = 30), and 32- (n = 25) month-olds. The proportion of child-initiated and prompted episodes increased with age, whereas that of mother-initiated episodes decreased, indicating that children are increasingly active partners.
Infant Behavior and Development
Grolnick, Wendy S.; Cosgrove, Thomas J.; and Bridges, Lisa J., "Age-graded change in the initiation of positive affect" (1996). Psychology. 492.